Effect of short-term ageing on high-temperature performance of SBS modified binder containing warm mix asphalt additives

Abstract

Warm Mix Asphalt (WMA) additives have been utilised to reduce working temperatures of Styrene-Butadiene-Styrene modified (SBS) binder to make sustainable pavement with enhanced pavement performance and lower energy consumption. Such modification may change the physicochemical structure of SBS binder and can influence rheological properties. The present study aimed at investigating the effect of short-term ageing on SBS binder containing various types of WMA additives. The experimental design included SBS binder, three WMA additives (Fischer Tropsch wax based- FT, chemical surfactant based- CS and water-based- WB) in three different dosages. The SBS binder was modified with mentioned WMA additives using a high shear mixer. In such way, 10 asphalt binders (one SBS binder and nine WMA modified SBS binders) were prepared. The short-term ageing of asphalt binders was performed using thin film oven. The high-temperature performance of unaged and short-term aged binders was evaluated using Superpave rutting parameter, high temperature performance grade (PG), multiple stress creep and recovery test (MSCR), and frequency sweep test. Based on the results, the short-term ageing showed an adverse effect on high-temperature performance of SBS binder, indicating degradation of SBS binder. Also, WMA additive type and dosages showed a significant effect on SBS binder in unaged and short-term aged condition. Considering the combined effect of WMA additive and short-term ageing, FT and WB additives reduced ageing susceptibility as well as improved rutting resistance of SBS binder. On the other hand, CS modification was able to lower ageing susceptibility, however, degraded high-temperature performance of SBS binder. Based on optimal high-temperature performance and lower ageing susceptibility, SBS binder can be modified with an effective dosage of 1% FT, 6% WB and 1% CS additive (by weight of asphalt binder).